This is an application on the relationships between specific cognitive functions and levels of gonadotropins and sex steroid hormones. The purpose is to build a hormonal cognitive function model to be useful in understanding the underlying cerebral factors of cognitive function. Since the review by the study section, a pilot study has been completed demonstrating a relationship between hormones and cognitive function. We propose to extend these findings by studying changes in these same hormone/behavior relationships within subjects with regard to endogenous changes due to diurnal or ultradian rhythms in men, or the menstrual cycle in women. We shall also compare the correlations of hormones and behavior across subjects as we had in our pilot study. But since we propose to test considerably more subjects, regression analyses will alow a finer picture of the complex relationships. In addition to the across-subject analysis and within-subject analysis for endogenous changes, we propose to study induced changes of either the gonadotropins (by administering clomiphene citrate) or testosterone (by injection) in men. The method of study is to draw blood for assays of gonadotropin, sex steroid and other hormones just prior to, during, and immediately following administration of subtests of the Cognitive Laterality Battery--a series of tests designed to measure spatial, orientational, sequential, and verbal (fluency) skills as well as general information processing. Correlations will be established by simple and multiple regression analyses between hormone concentrations and the different cognitive measures. Analysis of variance will be used to compare subjects within groups over different test sessions (endogenous changes) or condition (placebo or drug) (induced changes). Converging evidence of hormone/behavior relationships from across subjects or within subjects for the endogenous or induced hormone changes will be used to construct the hormone/cognitive function model. Our pilot study suggests there is an across-subject relationship between the concentrations of endogenous substances and cognitive processes. Once a hormonal/cognitive functiions model can be established it will not only aid in understanding the underlying factors of cognitive processes but should aid in the understanding of cognitive abnormalities already observed in such diorders as dyslexia. A hormone/cognitive function model is a necessary first step before the more ambitious step of studying the relationship between neurochemical systems and cognitive processes can be taken.